(Portland, OR) -- Republican Representative Greg Walden of Oregon is expressing concerns over Facebook's handling of user data. During a second day of testimony yesterday at the U.S. Capitol, Walden told Zuckerberg that while Facebook has grown, he worries that it hasn't matured. Walden also said that the American people are concerned with how Facebook protects and profits from its users' data. He also expressed curiosity on whether Facebook is keeping its end of the agreement with its users.